Terminal transferase expression in relapsed acute myeloid leukaemia

Terminal transferase positive acute myeloid leukemia: immunophenotypic characterization and response to induction therapy

A quantitative evaluation of terminal deoxynucleotidyl transferase (TdT) was performed using a highly sensitive enzyme immunoassay (EIA) in 72 previously untreated patients with acute myeloid leukemia (AML). Biological analysis of the leukemic cells included in all cases cytochemistry, search for Ph' chromosome and immunophenotyping with both anti-lymphoid and anti-myeloid monoclonal antibodies (MoAbs). Thirteen AML cases (18 per cent) were considered TdT+ by EIA. According to the FAB classification, almost all of them (12 out of 13) were within the M1 and M2 subgroups. A mixed lymphoid-myeloid phenotype was observed in one of the 13 TdT+ cases, while in none of the others were lymphoid features detected. Nine of the 10 EIA TdT+ cases studied in parallel were TdT positive with the conventional immunofluorescence assay. All patients received standard protocol chemotherapy and in 61 (13 TdT+, 48 TdT--) the response to induction treatment was analysable. Only 3/13 TdT+ patients (23 per cent) achieved a complete remission (CR), while in the TdT- group 38 patients had a CR (79 per cent) and 10 were resistant (p less than 0.01). It is suggested that the incidence, biological interest and prognostic significance of TdT+ AML should encourage the routine and more accurate search for this marker in all patients with AML.

Biphenotypic leukemia with unusual chromosomal translocation in a patient treated for melanoma

A patient in complete remission from malignant melanoma but with refractory anemia after nitrosourea treatment developed acute biphenotypic leukemia. This disease, progression was accompanied by expansion of a cytogenetically abnormal clone. At first cytogenetic analysis, 1 year post discontinuation of chemotherapy, only 25% of the metaphases examined were hypodiploid with monosomy 7. Six months later, all of the metaphases seen were 45,XY,-7. Six months before overt acute leukemia was diagnosed, an additional chromosome abnormality emerged, t(2;3)(q31;q27). Although the translocation was present in all metaphases examined, the patient progressed into an acute leukemia with two components: one TdT-positive, Ia-positive, and the other TdT-negative, Ia-positive, monocytoid antigen-positive. This mixed leukemia was identified by double fluorescence staining for intranuclear TdT and surface labeling with a monocyte-specific monoclonal antibody.

Monosomy 7 and multipotential stem cell transformation

Monosomy 7 was the sole karyotypic abnormality seen in a case of biphenotypic leukaemia involving both the myeloid and lymphoid lineages and in a case of de novo ALL undergoing a phenotypic shift to acute myeloid leukaemia at relapse. These observations suggest that monosomy 7 can be associated with transformation of a common lymphoid-myeloid progenitor cell.

Chronic anemia progressing to Auer rod-positive and TdT-positive acute leukemia with 5q- chromosomal anomaly

The 5q- syndrome is a recently described entity characterized by partial deletion of the long arm of chromosome No. 5 and by hematologic findings of chronic anemia with reticulocytopenia, nonlobulated megakaryocytes, and megathrombocytes. We report on a patient with the hematologic features of the 5q- syndrome who progressed to acute leukemia and whose uniqueness consisted of 1) lack of additional cytogenetic abnormalities, 2) presence of blasts with Auer rods, and 3) bone marrow cells positive for terminal deoxynucleotidyl transferase. His leukemia was refractory to conventional chemotherapy.

Terminal deoxynucleotidyl transferase (TdT) in human foetuses. An immunofluorescent and biochemical study

The liver, bone marrow and cord blood of 30 human foetuses between the 15th and 21st weeks of gestational age were examined. Liver suspensions were investigated both by immunofluorescent and biochemical assay; cord blood suspensions and bone marrow touches with immunofluorescent assay. The results indicate the existence of a few TdT+ cells in the liver, cord blood and bone marrow of human foetuses in the ages studied. The peaks for each organ were: 15 +/- 1.60 (mean +/- SD) TdT+ cells in the liver, 12 +/- 2 in the bone marrow and 18 +/- 2.83 in the cord blood. In all the organs TdT+ cells decrease in the later weeks. In the liver, the results of the immunofluorescent assay were confirmed by the biochemical activity.

Distinct lymphoblastic and myeloblastic populations in TdT positive acute myeloblastic leukemia: evidence by double-fluorescence staining

Double-immunofluorescent staining for the enzyme terminal deoxynucleotidyl transferase (TdT) as a marker of primitive lymphoblasts, and for the VIM-D5 antigen as a differentiation antigen of the myeloid system gave direct evidence for distinct lymphoblastic and myeloblastic populations (mixed leukemic cell populations) in seven patients with acute leukemia. The percentage of malignant TdT positive cells contributing to a leukemic cell bulk with unequivocal signs of myeloid origin was between 10 and 80%. A defect at the level of a common progenitor cell giving rise to both the TdT and the VIM-D5 positive blast cell population is discussed.

Terminal deoxynucleotidyl transferase in acute myeloid leukaemia

Between January 1980 and May 1981, 1966 marrow or blood samples from leukaemia patients were tested for terminal deoxynucleotidyl transferase (TdT) using nuclear immunofluorescence. The cells were also tested with a panel of immunological markers including monoclonal antibodies. Of 869 TdT positive cases detected, 555 were diagnosed as ALL and 32 as blast crisis of CGL; 226 were provisionally diagnosed as 'acute leukaemia' and finally diagnosed as ALL partly on the basis of immunological data; 56 TdT+ cases were provisionally diagnosed as acute non-lymphocytic or myeloid leukaemia; 266 cases of AML and 177 cases of CGL in blast crisis were TdT negative. Eleven of the above 'AML' cases were anti-cALL+ as well as TdT+ and were re-diagnosed and treated successfully as cALL. The remaining 45 were anti-cALL negative and finally diagnosed and treated, at least initially, as AML. Eleven of these cases had only 5-10% TdT+ cells which could have been normal, non-myeloid cells. Twenty cases had 11-50% TdT+ cells and 14 cases had 50-100% TdT+ cells. Of these latter two groups, details on 28 patients were available for evaluation. Three cases on review had no definitive myeloid cytochemistry and were haematologically AUL with a null-ALL phenotype (TdT+ DR+ cALL-). In 14 cases there was a large overlap (greater than 75%) of the proportion of cells with myeloid cytochemistry (Sudan black, peroxidase or esterases) and TdT; individual blast cells were therefore expressing these markers concurrently. In the remaining cases, mixtures of TdT negative myeloid and TdT+ (lymphoid?) cells may have coexisted although this was not proven unequivocally. Twenty-two cases of newly diagnosed TdT+ 'AML' received induction chemotherapy for AML (DAT regime) and only six (37%) obtained a complete remission. It is concluded that TdT positive 'myeloid' leukaemias do occur, albeit infrequently (approx. 5%) and may have a relatively poor prognosis.